A bit-serial approximate min-sum LDPC decoder and FPGA implementation

We propose a bit-serial LDPC decoding scheme to reduce interconnect complexity in fully-parallel low-density parity-check decoders. Bit-serial decoding also facilitates efficient implementation of wordlength-programmable LDPC decoding which is essential for gear shift decoding. To simplify the implementation of bit-serial decoding we propose a new approximation to the check update function in the min-sum decoding algorithm. The new check update rule computes only the absolute minimum and applies a correction to outgoing messages if required. We present a 650-Mbps bit-serial (480, 355) RS-based LDPC decoder implemented on a single Altera Stratix EP1S80 FPGA device. To our knowledge, this is the fastest FPGA-based LDPC decoder reported in the literature